Although chemical spills are somewhat common in semiconductor manufacturing, they are, for the most part, identifiable and safe to mitigate with proper personal protective equipment [PPE]. It is those times, when the chemical is non-detectable, that can be hazardous. The hazards resulting from a spill depend on variables that include the spilled material's chemical and physical properties, location, and quantity.
Some chemicals are difficult to detect even from a list of commonly available detectors, particularly those which are colorless, have low vapor pressure, and have a near neutral pH. Hydrogen fluoride (HF) readily dissolves in water to form colorless, extremely corrosive hydrofluoric acid solutions. HF solutions are visibly indistinguishable from water. However, HF solutions can be detected with a variety of detectors. In semiconductor manufacturing, HF solutions are commonly used for oxide etching, including solutions such as so called buffered HF (BHF). BHF is a neutral solution and generally comprises 40-45% Ammonium Fluoride; 0.49% Hydrofluoric Acid, with the remaining balance being water. BHF is thus an example of a chemical solution that is non-detectable outside a laboratory setting, even from a list of commonly available field detectors, since BHF is colorless, has a low vapor pressure, and has a neutral pH.
HF solutions are extremely hazardous. Such solutions can cause severe injury to any tissue with which it comes in contact (chemical burn). Exposure by contact with skin, or by inhalation or ingestion, can lead to severe toxic systemic effects (Acute Fluoride Intoxication) and potentially death. Death can occur from severe electrolytic imbalance (hypocalcemia and hypomagnesaemia) that leads to cardiac arrhythmia (fibrillation), which, in turn, can lead to cardiorespiratory arrest and multiple organ failure (kidney and liver).
HF is also easily absorbed by tissue, penetrating and then rapidly dissociating into Hydrogen and Fluoride. HF is highly corrosive and will destroy tissue, but the fluoride ion will also migrate through, and continue to damage bone. The disassociated fluoride ion will continue reacting to create fluorinated salts, which can cause serious toxic systemic effects. Washing the exposed tissue with water does not neutralize or stop the reaction, which limits the benefits of water washing (decontamination). HF-specific first aid treatments bind the fluoride to calcium, and rapidly starting such treatments is critical to stopping further tissue and bone damage. What is needed is a low cost, portable detector adapted for identifying the presence of certain target chemical solutions from unknown solutions, such as BHF solutions.